I've got a problem in my #4 cylinder. Every week and a half to two weeks the spark plug gets fouled out. It's like, something gets built up on the end of the plug, and then it won't fire. I've started keeping a spare plug, and whenever I notice it start to miss, I switch plugs and everything is fine. I plan on rebuilding the engine so that should cure it, but I was wondering if anyone had ever heard of, or had this problem before.